Contamination or serendipity – doing the wrong thing by chance

The Editors consider contaminant proteins.

Detecting the nature and solving the crystal structure of a contaminant protein from an opportunistic pathogen

A case of contamination from a Serratia bacterial strain that occurred while attempting to crystallize an unrelated protein from Burkholderia pseudomallei (overexpressed in E. coli) is presented. The procedures that were adopted to identify the contaminant based on crystallographic data only are presented and the crystal structure of Serrata spp. cyanate hydratase is briefly discussed.

Crystal structure of the Escherichia coli transcription termination factor Rho

A structure is reported of the E. coli transcription terminator factor Rho that was crystallized as an impurity present in preparations of an overexpressed bacterial membrane-transport protein.

Characterization and structure of glyceraldehyde-3-phosphate de­hydrogenase type 1 from Escherichia coli

The crystal structure of full-length glyceraldehyde-3-phosphate dehydrogenase type 1 (GAPDH1) from Escherichia coli was determined at 1.88 Å resolution. Analysis of the NAD⁺-bound form showed some differences between the structures of E. coli GAPDH1 and human GAPDH. As E. coli GAPDH1 shares 100% identity with GAPDH from Shigella sonnei, its structure may help in finding a drug for the treatment of shigellosis.

High-resolution structure of the alcohol de­hydrogenase domain of the bifunctional bacterial enzyme AdhE

The crystal structure of the alcohol dehydrogenase domain of AdhE from Escherichia coli is reported.

The structure of PfGH50B, an agarase from the marine bacterium Pseudoalteromonas fuliginea PS47

The structure of PfGH50B reveals a two-domain structure consisting of a β-sandwich CBM-like domain fused to an (α/β)₈-barrel catalytic domain. Key structural features that are likely to influence the nature of the reaction products and the enzyme processivity are revealed by structural comparisons.

Binding of inhibitors to active-site mutants of CD1, the enigmatic catalytic domain of histone de­acetylase 6

Histone deacetylase 6 (HDAC6) is an emerging target for the treatment of various diseases such as cancer through selective inhibition. While the second catalytic domain (HDAC6 CD2) has been extensively studied, comparatively little research has focused on the first catalytic domain (HDAC6 CD1). This work provides new structural insights regarding inhibitor binding to HDAC6 CD1 enabled by the study of active-site mutants.

Tetragonal crystal form of the cyanobacterial bicarbonate-transporter regulator SbtB from Synechocystis sp. PCC 6803

SbtB was crystallized in a new crystal form and was found to adopt a tetrameric conformation in the crystal rather than the native trimeric conformation. Cys94 was found to form intermolecular disulfide bonds between adjacent SbtB molecules in the crystal lattice.

Crystal structures of native cytochrome c₆ from Thermosynechococcus elongatus in two different space groups and implications for its oligomerization

The structure of native cytochrome c₆ isolated from T. elongatus was solved by X-ray crystallography and two different space groups were identified. The high-resolution structures and complementary biophysical characterization in solution indicate interaction interfaces that could enable distinct functionality in photosynthesis. In addition, a post-translational methylation is indicated.

The structure of the Moco carrier protein from Rippkaea orientalis

The structure of a Moco carrier protein from Rippkaea orientalis is presented together with evidence for its selective binding of the mononucleotide variety of molybdenum cofactor.